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Expressivity of sub property chains

From: Michael Schneider <schneid@fzi.de>
Date: Sat, 8 Sep 2007 14:53:48 +0200
Message-ID: <0EF30CAA69519C4CB91D01481AEA06A0409AAC@judith.fzi.de>
To: <public-owl-dev@w3.org>
Cc: <EZolin@cs.man.ac.uk>

Hi, list!

I wonder if it will be possible in OWL-1.1 to express (the one direction of)
the "uncle" relation 

    (?x hasParent ?y), (?y hasBrother ?z) -> (?x hasUncle ?z)

or not?

Until now, I always had the restrictions in mind as given by Evgeny Zolin's
DL Complexity Simulator [1]: There, "complex role inclusions" (the "R" in
"SROIQ" aka OWL-1.1), are shown in two variants:

    R - Complex role inclusions: 
        RoS \subseteq R, 
        RoS \subseteq S

So from this it seems that the upper role does always have to be one of the
roles in the chain. And with this restriction, the "uncle" relation would be
out of play.

But the OWL-1.1 draft [2] does not seem to make this restriction:  

    SubObjectPropertyOf(
        SubObjectPropertyChain(R1 ... Rn) S )

AFAICS, there seems to be no requirement that one of the chain properties
R_i have to equal the upper property S.

So, will I get my uncle, or not?

Cheers,
Michael 

[1] http://www.cs.man.ac.uk/~ezolin/dl/
[2] http://webont.org/owl/1.1/semantics.html#2

--
Dipl.-Inform. Michael Schneider
FZI Forschungszentrum Informatik Karlsruhe
Abtl. Information Process Engineering (IPE)
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Fax  : +49-721-9654-727
Email: Michael.Schneider@fzi.de
Web  : http://www.fzi.de/ipe/eng/mitarbeiter.php?id=555

FZI Forschungszentrum Informatik an der Universität Karlsruhe
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Received on Saturday, 8 September 2007 12:54:04 UTC

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